1. Field
The disclosed concept relates generally to electrical apparatus and, more particularly, to electrical apparatus, such as electrical switching apparatus. The disclosed concept also relates to racking assemblies for electrical switching apparatus. The disclosed concept further relates to couplings for racking assemblies.
2. Background Information
Electrical apparatus used in power distribution systems are often mounted within an enclosure either individually or in combination with other electrical apparatus (e.g., without limitation, circuit switching devices and circuit interrupters such as circuit breakers, contactors, motor starters, motor controllers and other load controllers; potential transformers; control power transformers; fuses).
Some electrical switching apparatus such as, for example, some medium-voltage and low-voltage circuit breakers, can be relatively large. In order to facilitate movement (e.g., installation; removal; maintenance), some circuit breakers are commonly coupled to draw-out mechanisms which permit such circuit breakers to be drawn out of the switchgear enclosure. Accordingly, such circuit breakers are commonly known in the art as “draw-out” circuit breakers. The circuit breaker may be further supported within a draw-out frame, commonly known in the art as a cassette or chassis. The switchgear enclosure generally includes a number of cells, with each cell being structured to receive a corresponding circuit breaker. The draw-out mechanism includes, for example, a combination of rails and rollers coupled to one or the other, or both, of the sidewalls of the cell and the sides of the corresponding circuit breaker and/or cassette, which is to be drawn into and out of the cell. A racking assembly (sometimes referred to as a “lev-in” device), which among other components includes a drive screw and drive rack, facilitates levering the circuit breaker into the cassette. Draw-out circuit breakers are described in further detail, for example, in commonly assigned U.S. Pat. No. 7,019,229, which is hereby incorporated herein by reference.
To enhance safety, it is desirable to avoid manual manipulation of the circuit breaker from close proximity and instead enable remote operation of the lev-in device from a distal location. However, some known medium voltage circuit breakers, for example, have a safety feature incorporating an interlock slide bracket or slider that must be moved (e.g., without limitation, moved inward) to trip the circuit breaker before it can be racked in or out. This operation is typically manually performed by an operator, and typically must be performed through an opening in the door which can expose the operator to hazards.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in racking assemblies and couplings therefor.